Polypropylene is a preferred material for use in forming plastic articles. However, a problem with polypropylene is its general surface softness, especially its susceptibility to scratching. Resins having harder surface character are often added to polypropylene to improve its toughness. When these resins are added, however, they are often not found on the surface of the articles formed from the polymer blends. It is desirable to have polyolefin compositions which have good surface hardness and have improved toughness, especially improved scratch resistance.
U.S. Pat. No. 5,230,963, issued to Knoerzer, relates to oxygen and water vapor transmission resistant film and methods of making the same. The film is a combination of base layers each of which is a blend of polypropylene and maleated polypropylene. Each of the layers receive a coating of polyvinyl alcohol and a crosslinking agent.
U.S. Pat. No. 5,248,364, issued to Liu et al, relates to polypropylene laminates and processes for the production thereof. The laminate contains a layer composed of a blend of maleated high molecular weight polypropylene and a low density polyethylene.
U.S. Pat. No. 5,281,670, issued to Lee et al, relates to polyolefin compositions. The compositions comprise a blend of polybutylene and a functionalized polyolefin, such as maleated polypropylene.